Genes regulating cell cycle progression in the Drosophila developing eye will be studied. The roughex gene is involved in preventing progression into the synthesis phase of the cell cycle in cells of the developing eye. A weak allele of this gene can be suppressed by other genes that become candidates for other genes involved in cell cycle control. The identification of some of these genes as components in cell cycle control (as known regulators of cyclin-dependent protein kinases) establishes the ability of this screen to identify the desired genes. This proposal focuses on two genes that were not previously identified as involved in cell cycle control. The first specific aim is to characterize the cell cycle phenotype of these two mutants. This will be done by examination of the phenotype obtained in the developing eye disc and in the embryo. Specific aim two is to carry out a molecular analysis of the genes. There is good preliminary data showing that strategies have been developed that should lead to the cloning of these two genes. The information from the cloned genes will be used to prepare antibodies to detect the proteins in embryos and in eye discs. The third specific aim will investigate the function of these two genes. The first line of inquiry will be a genetic approach with other genes involved in cell cycle control to determine if the gene can be placed in a pathway. The second line of investigation will determine if the protein binds to any known cell cycle proteins.